This invention relates to the discovery and asexual propagation of a new variety of grapevine, Vitis vinifera cv. `Sugrasixteen` . The new variety was first hybridized by David W. Cain in Wasco, Kern County, Calif., the variety being originated by controlled hybridization and subsequent ovule culture of normally abortive seeds. The new variety is characterized by producing black grapes having very small, vestigial seed traces that are not noticeable when eaten. The new variety is highly productive and may be spur pruned to two bud spurs.
The seed parent is the `Black Monukka` variety (unpatented) and the pollen parent is `Sugrafive` (U.S. Plant Pat. No. 5,151). The parent varieties were first crossed in May, 1988, with the date of first flowering being May, 1991. The new `Sugrasixteen` variety was first asexually propagated by David W. Cain in December, 1991 in Wasco, Kern County, Calif., using cuttings.
The new grapevine variety cv. `Sugrasixteen` most nearly resembles its seed parent the `Black Monukka`. It differs from the `Black Monukka` by ripening approximately 7 days earlier, by having firmer flesh and tougher skin, by having a much smaller and less lignified seed, and by possessing a distinct vinous muscat flavor.
`Sugrasixteen` is distinguished from other commonly grown black seedless grapes such as the `Beauty Seedless` (unpatented), `Fantasy` (unpatented), `Larson B-36` (U.S. Plant Pat. No. 9,039), `Mariah` (U.S. Plant Pat. No. 9,040), and `Marroo` (U.S. Plant Pat. No. 7,377) by possessing a highly desirable, strong, distinct, vinous, fruity flavor most nearly similar to that commonly referred to as muscat but differing from the flavor of commonly known muscat grapes such as the `Muscat of Alexandria,` `Muscat Hamburg,` and `Italia` varieties (all unpatented).
The new variety further can be distinguished from the above cited varieties by possessing a much thicker, stronger and more highly lignified rachis which provides superior handling characteristics during commercial harvesting and shipping procedures. The region of the peduncle most proximal to the cane often becomes brown and woody while the peduncles of the above cited varieties most often remain green and less woody than the new variety.
The new variety ripens later than the `Beauty Seedless,` `Larson B-36,` and `Mariah` varieties and ripens more nearly with the `Fantasy` and `Marroo` varieties. It is moderately responsive to gibberellic acid applications to reduce berry number and to increase berry size, but high levels induce phytotoxicity and increase berry shatter during harvest shipping.
The new `Sugrasixteen` variety has been shown to maintain its distinguishing characteristics through successive asexual propagations by, for example, cuttings.